1. Field of the Invention
The present invention relates to a mounting structure for an in-vehicle device, such as a car audio system or a car navigation system, mounted in a vehicle using a bracket, and in particular, relates to improvement of the bracket.
2. Description of the Related Art
Since such an in-vehicle device is often installed on an instrument panel or the like in a vehicle, for example. The head of an occupant may collide with the in-vehicle device upon sudden braking. Furthermore, while moving, a vehicle is susceptible to vibrations in left and right directions and up and down directions depending on a road surface. If the vehicle is moving over a bumpy road, the interior of the vehicle will be shaken violently. To mount an in-vehicle device to an installation member of the vehicle with a bracket, therefore, the bracket should have necessary stiffness so that the mounting position of the device is not shifted due to, for example, vibration caused while the vehicle is moving. In addition, consideration should be given to safety so that if the body of an occupant collides with the in-vehicle device, damage to the occupant can be reduced.
To meet such demands, an in-vehicle device mounting structure has been proposed as disclosed in, for example, U.S. Patent Application Publication No. 2007/0223137 A1. In this mounting structure, a guide member (vibration damping element) having a slot that extends in front and rear directions is secured to an installation member of a vehicle and a fastener is secured to an in-vehicle device. This fastener is usually retained such that the fastener engages the slot at a predetermined position. If a strong impact is applied to the in-vehicle device from the front side (occupant side), the fastener can translate backward along the slot. In this related art, since the fastener is usually retained at the predetermined position within the slot of the guide member, the mounting position of the in-vehicle device is not shifted even when vibrations in the left and right directions and/or the up and down directions are applied to the in-vehicle device while the vehicle is moving. Furthermore, if the body of an occupant collides with the in-vehicle device upon sudden braking, the impact of collision causes the fastener to slide backward within the slot against a retaining force, so that the in-vehicle device moves backward simultaneously with the sliding. Accordingly, an excessive reaction force does not act on the occupant, such that damage to the occupant can be reduced.
In the above-described related art, however, it is difficult to avoid variations of the retaining force for holding the fastener at the predetermined position within the slot of the guide member. Disadvantageously, therefore, an occupant may not be sufficiently protected against a strong impact. Alternatively, the mounting position may be shifted even if the occupant accidentally pushes the in-vehicle device at a pressure of an ordinary level which may be applied in everyday life. Specifically, if the occupant collides with the in-vehicle device and the fastener cannot translate along the slot because the retaining force applied to the fastener in the guide member is too strong, a strong reaction force applied from the in-vehicle device, which is inhibited from moving backward, will act on the occupant. This is undesirable in terms of safety. On the other hand, if the retaining force applied to the fastener in the guide member is too weak, the mounting position of the in-vehicle device may be shifted even when a person or object slightly contacts the device. This is unfavorable in terms of performance retention.
Furthermore, in the above-described related art, in the case where an occupant collides with the in-vehicle device and the fastener slides backward within the slot, impact applied from the occupant cannot be effectively absorbed because the fastener merely moves backward against frictional force in the slot. Accordingly, when the occupant collides with the in-vehicle device and the device moves backward only slightly, a strong reaction force may act on the occupant.